WPF Line of Business Application XAML Layouts Presentation
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This document provides an overview of panels and layout in WPF. It discusses the built-in panels like Canvas, StackPanel, WrapPanel, DockPanel and Grid. It also covers layout properties, transforms, creating custom panels, and the two phase layout process of measure and arrange.
Editor's Notes
- #7: Panels are responsible for the layout of a collection of UIElement-derived children. When the Measure method is called on a panel, it must measure all its children. When the Arrange method is called on a panel, it then must arrange its children.
- #16: The Grid layout panel positions child elements within rows and columns. By default there is only a single row and column in to which all elements are placed.Each child element is positioned within the grid by using attached properties:Grid.RowGrid.ColumnGrid.RowSpanGrid.ColumnSpan
- #17: The Grid layout panel has two collections for managing rows and columns: RowDefinitions and ColumnsDefinitions respectively. The RowDefinitions collection is populated by using RowDefinition objects and theColumnsDefinitions collection is populated by using ColumnDefinition objects.The RowDefinition class defines a Height property of type GridLength and ColumnDefinition defines a Width property also of type GridLength. Combining these property values creates the layout for the grid. The GridLength class enable values beyond simple numbers to be assigned to the height and widths of rows and columns, values such as “Auto” and “*” can also be applied.Auto. The size is determined by the content.*. Uses all the available space to the panel, and is also used with “Star Sizing”, covered in the next topic.
- #28: Transforms can be used throughout WPF to effect the size, shape and position of elements. A transform defines how to map points from one position to another position by using a transformation matrix. Applying the transformation matrix to certain values, depending on the transformation required, on a target object delivers the rotation, skew, scale, and move transformation effects. All transforms in WPF are affine transforms. An affine transform is a mathematical transformation that preserves parallel lines. All 2D transforms derive from System.Windows.Media.Transform class.ScaleTransform. Scales an object in the 2-D x-y coordinate system.TranslateTransform. Translates (moves) an object in the 2-D x-y coordinate system.SkewTransform. Skews an object in 2-D space.RotateTransform. Rotates an object clockwise about a specified point in a 2-D x-y coordinate system.TransformGroup. Transforms can be combined using a TransformGroup object.
- #29: Any RenderTransform is applied immediately before rendering, therefore only having an impact on the rendering, as opposed to have an impact on layout.
- #30: Any LayoutTransform is applied before layout, therefore affecting the layout of the FrameworkElement. Translate transforms are ignored in LayoutTransform.
- #31: You can use the sample XAML file <install path>\\Module 03\\Demos\\Transforms\\TransformTypesExample.xaml to help with the demonstration.Show the impact of applying the transforms to the following properties:RenderTransformLayoutTransformYou can use the sample XAML file <install path>\\Module 03\\Demos\\Transforms\\TransformsExample.xaml to help with the demonstration.
- #32: WPF contains several layout elements: Canvas, StackPanel, DockPanel, Grid, etc.
- #33: There are usually two reasons to create a custom panel: Performance Algorithmic LayoutCreating a new panel for performances reasons is a rare occurrence; but, for example the UniformGrid was created for performance reasons.Algorithmic layout means a layout that is based on a algorithm as opposed to positional layout; for example, child elements positioned along a circular path.To write a custom Panel inherit from Panel. WPF has a two phase model for layout, a measure and a arrange phase; the MeasureOverride and ArrangeOverride methods must be implemented. It is very important that in each phase you call the appropriate Measure and Arrange methods on each child; or it is very likely WPF will not render the child element.A great example of custom panels can be found in “Kevin’s Bag-o-Tricks”, a whole host of WPF custom feature implementations, including panels, a great tool for learning how WPF works and how to extend it: http://j832.com/bagotricks/